For more than 400 years the Catholic Church maintained a list of prohibited books.

Such a list was officially first issued during the reign of Pope Paul IV (1555-59) and frequently was revised until 1966, when the list was ended. Historically known as the Index of Prohibited Books, it impacted printers, readers and authors alike. But why did the Church get into the business of prohibiting books? What was the purpose behind denying certain books to Catholics?

The Catechism of the Catholic Church states that the Church magisterium, its teaching office, is tasked “to preserve God’s people from deviations and defections and to guarantee them the objective possibility of professing the true faith without error” (No. 890).

In the early centuries of the Church such deviations, defects or falsehoods were largely spread by the written word. As a result, the Church sought to limit certain written materials — specifically, unauthorized vernacular translations of the Bible, books and other literature authored by heretics, superstitious works such as astrology and magic, obscene works and books promoting philosophies not sanctioned by or in accordance with Church teaching.

Confronting Heresy

Scripture scholars often cite the Acts of the Apostles as biblical evidence of dangerous books being destroyed (see 19:16-19). In Acts, Paul is depicted as traveling throughout Ephesus, teaching the Gospel as well as curing the sick in the name of Jesus. Jewish exorcists or magicians also invoked the name of Jesus, in the manner of Paul, while attempting to drive out demons and cure the afflicted. They were unable to do so. The magicians immediately realized that the grace and gifts from Jesus were much stronger than any magic power to which they could lay claim. As a result, they sought to become followers of Christ and, to prove their sincerity, voluntarily burned the books that contained their “magic” formulas.

The Council of Nicaea is an early instance where writings were burned by Christian leaders. At that council in 325, Emperor Constantine called all the Church bishops together to deal with the heresy of Arianism that claimed that Jesus was not God. The council condemned and excommunicated both Arius and his followers. Subsequently, Constantine directed that all the writings of Arius be burned so that his philosophies could not pollute anyone else.

As Christianity began to take root, there was a need to determine the legitimate books that should make up the Old and New Testaments. There were many opinions regarding which writings were divinely inspired and those that were not inspired. In 405, Pope Innocent I sought to clarify the situation in a letter to Bishop Exsuperius of Toulouse, specifying the books accepted as canonical — that is, those that should be included in the Bible.

The letter also enumerated and condemned writings that were not proven to be genuine, or were considered forged or illegal, including works alleged to have been written by the apostles John and Peter, and others by Matthias, James the Less, Leucius, Andrew, Nexocharis, Leonidas and Thomas. In 496, Pope Innocent’s list of condemned writings was included in an official papal decree, Decretum Gelasianum, attributed to Pope Gelasius I (r. 492-496).

There were other instances in the early Church when writings were banned or burned. In 435, Emperor Theodosius II had all the writings of Nestorius of Antioch destroyed because Nestorius advocated that Mary was not the Mother of God. In 446, Pope Leo I the Great ordered books destroyed that advocated positions not in accordance with Church teachings and directed punishment of individuals who read or possessed those books. Following the Third Council of Constantinople, held in 680, writings associated with the heresy of monothelitism were also burned.

The writings of the heretical Albigensians were burned in the 12th and 13th centuries. Likewise, during the 15th century, the books of John Wycliffe and John Hus were banned or burned. Selected books promoting Jansenism were also condemned in the 17th and 18th centuries.

The Rise of Printing

Until the 15th century all writing was done by hand, mostly by monks, and there existed few copies of any one publication. Thus the Church could mostly control books that it found contrary to the teachings of Jesus. That kind of control forever changed with the invention of the printing press in 1440.

During the Fifth Lateran Council (1512-17), the bishops acknowledged the value of the printing press, but wrote: “Complaints [as a result of the printing press] from many persons, however, have reached our ears and those of the apostolic see. In fact, some printers have the boldness to print and sell to the public, in different parts of the world, books … containing errors opposed to the faith as well as pernicious views contrary to the Christian religion and to the reputation of prominent persons of rank. The readers are not edified. Indeed, they lapse into very great errors not only in the realm of faith but also in that of life and morals” (Tenth session, May 4, 1515, promulgated by Pope Leo X’s bull Inter sollicitudines).

The council then directed that no book could be printed, under threat of excommunication, without approval of appropriate Church officials.

Clearly the Church of the times worried about the impact of the printing press on the moral fiber of the laity, and worries heightened with the 1517 revolt of Martin Luther. Luther’s theology and the capability to spread that theology led to the first printed Vatican list of prohibited books, historically known as the Index Prohibitorum, or Index of Prohibited Books. Issued by Pope Paul IV in 1559, this index was part of the 16th-century Roman Inquisition that was created to counter the spread of Protestant heresy. Protestant writings were often burned, and individuals possessing the books were punished.

The famous Council of Trent, summoned to implement a thorough reform in the Church and held in several sessions from 1545 to 1563, took as one of its later objectives to establish a separate commission to draw up a new list of forbidden books. This list, known as the Tridentine Index, was issued in 1564 by Pope Pius IV and not only included a list of banned books but the guidance and procedures used during all future revisions and changes to the index.

In April 1571, a formal office was decreed for overall responsibility to deal with the issue of prohibited books. This organization was called the Sacred Congregation of the Index. In addition to maintaining the index, it was charged with identifying necessary corrections that would make a particular work acceptable. While over the centuries the name of this congregation would change and its authority amended, the congregation would carry out its duties of responding to false teachings and heretical writings until the mid-20th century.

Revisions to the Index of Prohibited Books differed in manner of presentation and content. The first list issued, in 1559, forbade all the works of certain authors, selected works of other authors, books written by heretics and erroneous translations of the New Testament in the vernacular. That index also contained the names of 61 printers whose works were banned. As expected, the Council of Trent focused primarily on printed materials authored by Protestants.

A significant change to the index came during the reign of Pope Benedict XIV who, in 1753, issued enhanced rules on the process of censoring new books and how the rules would be enforced. His bull Sollicita ac Provida clarified that any written material in question had to be examined by nonpartisan scholars and two of three had to agree that the book should be banned. The recommendation of the scholars was then sent to a committee of cardinals for a decision.

Following the First Vatican Council, and during the tenure of Pope Leo XIII (1878-1903), revisions gave more attention to principles that would guide Catholics in discerning what they should read. The last index was published in 1948 and included 4,000 titles.

In 1966, the Sacred Congregation of the Holy Office, the congregation responsible for the Index of Prohibited Books, was reorganized in accordance with the apostolic letter Integrae servandae, issued by Pope Paul VI. The letter renamed the congregation the Congregation for the Doctrine of the Faith and established rules for the congregation, but made no mention or reference to the Index of Prohibited Books.

When the newly formed Congregation for the Doctrine of the Faith received inquiries regarding prohibited books, they responded that the index no longer enjoyed the force of Church law and was thus suppressed. The response went on to indicate that the ethical obligation of not distributing or reading books that impact morals and faith still exists, and that this was not a compromise. The responsibility for avoiding such material is now on the conscience of the faithful under the guidance of the bishops. While the Index of Prohibited Books has been ended, the Church will always act as necessary to guard against the “gangrene” of false teachings (see 2 Tm 2:17) and will always preserve the deposit of Christian faith and protect the true message of Jesus Christ.

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